HEAT INSULATION OF ROOFS AND FLOORS

Abstract: This invention relates to the heat insulation of roofs and floors. In accordance with the invention the surface (1) is covered with a heat-insulating material (2), and supports (4) are placed on the said heat-insulating material (2). A monolithic, rigid and waterproof shell (7) is then placed, on the supports (4) so that an air-gap (3) is formed between the said heat-insulating material (2) and the said shell (7) and so that the said shell (7) may slide on the said supports (4). The ability of the finally constructed shell (7) to slide freely on the supports (4) actually protects the shell (7) from cracking due to overheating and overcooling. Further, according to the invention, the air-gap (3) communicates with the outer-space, a feature ensuring ventilation of the air-gap (3) and consequently preventing the development of moisture on the heat-insulating material.

Description: HEAT INSULATION OF ROOFS AND FLOORS This invention relates to the heat insulation of roof and floor surfaces. Further the surfaces insulated in accordance with the invention are waterproof and soundproof. As an example of floor surfaces, reference is made to interior floors, building terraces, quays etc. As far as roof elements are concerned, reference is made for instance to horizontal and inclined roofs, domes etc. In treating the issue of waterproofing and heat insulation of horizontal surfaces, the state of the art refers to various methods, which are mainly based on the use of membranes made of all kinds of asphaltic or other synthetic material available by the chemical industry, such as PVC, polyurethane ' s, polyethylene, polypropylene, styrene, acrylics and others. Such membranes, which either are applied in liquid form or they are ready sheets, are used for waterproofing of the external horizontal surfaces of buildings and ensure protection from internal or external wetting of the heat insulation layers. The main disadvantages that such material present, are i) the limited life-time of their properties, because of their exposure to a high- temperature environment and/or ultra-violet radiation, and ii) that they may be easily perforated. There is also a risk of having defective joints, when adjacent membrane elements, are joint together. The use of such membranes is further involved with a relatively high cost. The water, which accumulates on such surfaces, is guided towards drainage openings configured around the perimeter of the surface, whereby the water flow is achieved through an appropriate inclination configured thereon. The inclination is obtained through application of various materials of considerable thickness such as light concrete, pumice-stone, gas-concrete etc., or through the covering of the surface by plates whose upper surface is inclined in their final position. This process is costly and results in loading the surfaces to be insulated, with additional weights. When the surfaces are intended to be passable and/or to carry heavy loads, they are usually covered with a concrete layer (see for example figure 2 of document US-A-4,674,249). The problem which in such cases arises is the development of cracks, as a result of thermal loading. In order to minimise this problem expansion joints are formed, which are usually sealed with appropriate organic materials of synthetic base, having a limited life-time, which calls for due inspection and maintenance works on a regular basis. To minimise the effect of environmental factors and the various mechanical loading to which insulation membranes are subjected, the solution of the so-called reversed roof has been suggested. In accordance with this method, the waterproof membrane is positioned under the heat-insulating layers, i.e. between the surface to be insulated and the heat insulating layers. In this case, it is absolutely necessary to use heat-insulating materials with high resistance to the absorption of water and/or humidity, as for instance certain foam synthetics with closed cells or foam glass. A disadvantage linked with all processes based on the use of membranes, is that the membranes, which also act as a damp barrier, do not allow for the proper ventilation of the various construction elements. The particular solution of the reversed roof, present a further disadvantage, that it allows the water and ice to surround the heat-insulating coating and to further remain trapped within. Moreover, due to their location, the insulating material is affected by the solar thermal radiation and the mechanical strain caused by the latter. In accordance with another solution and in order to ensure the passability of the surfaces to be insulated, panels or concrete plates are used, which are placed over the heat-insulating layers. In view of this solution it has been suggested, that the plates are to rest on the insulating layers thanks to appropriate supports of limited dimensions, thus allowing for an air-gap to be left underneath the plates (see for example figure 1 of document FR-A- 2240332. According to another arrangement the heat-insulating material is fixed underneath the concrete plates, which are then directly placed on the waterproof membranes. Nevertheless, in both cases mentioned above -namely, in the case of an air-gap underneath the concrete plates and in the case of having the heat-insulating material attached to the plates, the use of waterproofing membranes is by all means necessary, because the final external surface consists of a multitude of plates, the joints of which are permeable by water. The present invention aims at establishing a technically flawless, low-cost and time saving process allowing for the thermal insulation of roofs and floors. The invention is defined in claims 1 and 8. The combination of the features in accordance with claim 1, allows for the construction of monolithic shells without expansion joints and with excellent waterproof qualities. Thus, the constructed shells are passable, and in combination with the air-gap over the heat-insulating material ensures, the perfect insulation of the surface. The construction is relatively cheep, both in terms of money and time. The ability of the finally constructed shell to slide freely on the supports actually protects the shell from cracking due to shell overheating and overcooling. Communication of the air-gap with the outer-space ensures ventilation of the former and is consequently expected to prevent the development of moisture on the heat-insulating material. In this way, the properties of the heat-insulating materials are properly and efficiently preserved on a stable level. Thanks to these characteristics and features of the invention, the use of any kind of water¬ proofing membranes - a common feature of the known methods - is avoided. Further, wetting of the heat-insulating material is avoided, because the shell is monolithic, without joints, and accumulation of humidity is effectively limited, because membranes, whose use does not allow for the proper ventilation, are not used. Thus possibility is given for application of all kinds of heat-insulating materials, such as fibreglass, fibre stone etc., which are highly resistant to heat and provide efficient sound-insulation. It is further also to be mentioned that, according to the features of the invention, the method ensures not only monolithic qualities and the continuity of the shell itself but the continuity of the heat-insulating material since the various supports are placed on the heat-insulating material, and do not perforate it. Claims 8 defines a heat insulating structure on the outer surface of a roof or floor, comprising all the features of the invention. Dependent claims 2 to 7 and claim 9 refer to particular embodiments of the invention, providing further advantages. Claim 2 represents an embodiment of the invention according to which water collectors and piping are installed within the air-gap, ensuring collection and siphomc flow and disposal of the liquids, which accumulate on the surfaces In this way the construction of the inclinations of the prior art, which have been already described in the third paragraph on page 1, to guide the water on the disposal points is avoided This embodiment of the invention is particularly advantageous in the case of surfaces, the geometry of which does not favour a natural flow of water (as is, for instance, the case with horizontal surfaces), as well as in cases of platform surfaces upon which liquids easily accumulate, as is the case of railway stations quays or slaughter-house floors According to claim 3, a ventilation channel is provided on the water collector, to allow further ventilation of the air-gap Further, according to claim 4, a thread is provided on the channel ' s wall, to screw a ventilation pipe In this way, the connection of the ventilation pipe and the ventilation channel is waterproof Claim 5 refers to a particularly simple and efficient construction of the shell, from reinforced concrete According to this claim, an assembly is placed or constructed on the supports, and then concrete is applied over it According to claim 6, the shell perimeter is to remain free, so that the connection of the air-gap with the outer-space is ensured in a peπmetπc way In order to achieve this connection, in case of existence of a parapet, the perimeter of the shell is not connected thereto Claim 7 defines the application of the method on a curved surface, for instance the external surface of a dome According to claim 9 the layer of the heat insulating material is placed on the roof element and below the supports, and that the supports abut the heat insulating material Following is the description of an embodiment of the invention, whereby reference is made to the figures 1-6 Figure 1 illustrates an insulated surface with the heat insulating structure. Figures 2 and 6 illustrate the water collector and the respective piping in the final operational position. Figure 3 illustrates the water collector. Figures 4 and 5 illustrate the perimeter of the shell, which remains free. Figure 1 presents the roof of a building (1) carrying the heat insulating structure in accordance with the invention. Apart from the surface (1), the figure shows the heat-insulating material (2), the ventilation air-gap (3) and the shell (7) made of reinforced concrete. Supports (4) having wide flanges, which are not shown in figure 1, have been placed in the air-gap (3) between the heat-insulating material and the shell (7). The shell surface (7) is further divided in approximately square areas (for example δOrrr) such as the one shown in Figure 1, on which slight inclinations, have been formed at the stage of the application of concrete; they converge towards the geometrical centre of the area where the collector inlet (8a) is situated. The collector (8) which, along with the pipe (9) connected to it, constitute the siphonic assembly of the drainage system, are immersed in the ventilation air-gap (3) and abut the heat-insulating material (2) without being connected by any means thereto. The pipe (9) further extends vertically from the point of descent from the surface (1) and to such length as required for siphonic flow of the liquids. Figure 2 shows the way of installation of the of the collector (8) and the ' pipe (9), which are positioned freely on the heat-insulating material (2). Figure 3 shows an embodiment of the water collector (8), having an outlet (8β) formed in its lower part. The collector (8) further comprises a ventilation channel (8 ' ) for ventilation of the air-gap (3), the function of which is described further below. On the upper opening (8 " ) of the channel (8 ' ) (see figure 2) which, upon setting the collector to its operational position lays outside the air-gap (3), a ventilation pipe of appropriate length is threaded. Figures 4, 5 and 6 show the arrangement of the wide-flange supports (4) on the heαt-insulαting material surface (2), as well as the covering of the latter with thin yet, at the same time, not easily flexible sheets (5) with the concrete reinforcement (6) placed upon them. The sheets (5) together with the said reinforcement (6) actually form an assembly (5, 6) to be used as a framework for the concrete, which will be eventually applied. Figure 4 presents the arrangement of a communication opening (3 ' ) between the shell (7) and the parapet (lO). Such a communication opening (3 ' ) allows for communication between the air-gap (3) with the outer- space. According to the way shown in figure 4, the sheet (5) is to be adequately bent around the parapet area (lO) in a way to form the angle (5') required. Such an angle could just as well be obtained by means of positioning a sheet having an L-shaped cross section. Figure 5 shows the shell (7) with the communication opening (3 ' ) between the shell perimeter (7) and the internal surface of the parapet (lO). The structuring of the communication opening (3') allows for an unobstructed motion of the shell (7) under the influence of temperature variations. In order to assist the unobstructed motion the shell may not be attached to any other element of the building such as a chimeney. The shell (7) slides freely on the support flanges (4) while, at the same time, the said communication opening (3') allows for ventilation of the air-gap (3). In this way, the heat- insulating material (2) is kept dry, which results in the stability of its heat- insulating properties. As a general rule, ventilation obtained through the communications opening (3 ' ) as well as through the air-gap (3) allows for the establishment of milder temperature conditions on the heat-insulating material (2) surface on periods of potential overheating and/or overcooling of the shell (7) as well as in the case of high speed winds. In order to protect the communication opening (3 ' )- a cover (11) made of appropriate material is positioned as shown in figure 5. Figure 6 shows the arrangement of the shell (7) in area around the collectors (8). The collector (8) is connected in a perimetric way with the reinforcement (6) and, in a perfectly waterproof way, with the shell (7), while at the same time it is freely based on the heat-insulating material (2) in a way to ensure sliding of the collector (8) in conformity with the movements of the shell (7), due to thermal charge. The collector (8) undergoes these movements along with the pipe (9) which is connected to the outlet (8b) of the collector (8). Figures 3 and 6 show the ventilation channel (8 ' ) arranged within the collector (8). The channel (8) has a first opening (8 " ) which, at the operational position of the collector (8) lays outside the air-gap (3) and a second opening (8 '" ) which, lays within the air-gap (8). The said ventilation channel (8 ' ) connects the air-gap (3) with the outside area thus allowing for ventilation of the air-gap (3). On the first opening (8 " ) of the channel (8 ' ), which in this specific case is cylindrical, there is an appropriate thread to ensure a waterproof connection of the channel (8 ' ) with a ventilation pipe of an appropriate height. Both in the outlet (83) and inlet (8a) and the first and second (8 " ,8 '" ) openings there has been provision for special filters to purify the water flowing there through. Filters are also provided in the piping ends (9), . In the following paragraphs, the application of the method to insulate a surface, in accordance with the invention is described. Surface (1) is covered the heat-insulating material (2) in uniform thickness. Further, the total surface is divided in approximately square sections (for example, δOrrr). On the geometrical centre of each section a collector (8) is placed, which is appropriate for collection of the liquids eventually accumulate on the section. Each collector (8) is then connected to an horizontal pipe (9) which extends up to the point of descent from the surface (1); at this point, the pipe is bent (9) and further continues to extend to a vertical direction up to a certain length, so that requirements of siphonic flow are met. Both the collector (8) and the pipe (9) on its horizontal part are freely based on the heat-insulating material (2), without any anchoring points. Wide-flange supports (4) are placed, but not fixed, on the heat-insulating material (2) at appropriate spacing, so that the supports may slide thereon. Thin rigid sheets (5), preferably metallic, are then positioned on the free (upper) flanges of the supports (4) The sheets (5) bridge the supports and cover the whole surface to be insulated, with the exception of the inlets (8a) of the collectors (8), which remain free. Further, these sheets (5) do not allow fluid concrete to penetrate them and thus they form a framework for the fluid concrete to be eventually applied on them. The area of the flanges and the number and spacing of the supports (4) are selected to assure a uniform loading of the heat-insulating material (2), and thus to minimise the deformations to be developed. The sheets (5) create a surface covering the surface (1) to be insulated, under which there is an air-gap (3) allowing for ventilation of the heat-insulating material (2). The height of the air-gap (3) is enough to cover the collectors (8) as well as the pipes (9). Care is taken to ensure low friction coefficients on contact points between the supports ' flanges (4) and sheets (5). Along the perimeter of the surface (1), where the building parapets (lO) exist, the sheets (5) are vertically bent, or alternatively L-shaped elements are positioned in a way to form an opening (3 ' ) allowing for communication of the air-gap (3), with the outer-space. On the sheet surface (5), a metallic concrete reinforcement (6) is placed. The next step is the application of concrete on the assembly (5,6) thus formed - the assembly consists of the sheets and the reinforcement,, so that the concrete shell (7) is formed. The reinforcement (6) ensures resistance to the various tensions eventually developing within the shell, as a result of load charges and, of thermal loads; in this way, the shell shall be preserved crack-free. The composition of the concrete as well as all other material eventually to be added to the latter, aim in improving its properties, and ensure, among other, a crack-free surface and full water- tightness. Further the shell is passable, i.e. people may walk on it, and its properties are not influences from the environmental conditions. Slight inclinations are formed on the shell (7) around the collectors ' inlets (δa), a step followed by the smoothening process of the concrete surface. The communication opening (3 ' ) may be covered with appropriate protective elements (11). Apart from allowing for an unobstructed contraction and expansion of the shell (7) the communication opening (3 ' ) also allows ventilation of the air-gap (3). Ventilation is further achieved through the ventilation channel (8'). The method may be applied to horizontal, plane, curved or corrugated surfaces. The advantages of the method in accordance with the invention may be summarised as follows : • It is not required to use any kind of waterproof membranes. • The protection of the heat-insulating material by the monolithic shell, the ventilation achieved through the air-gap and the absence of membranes allow the use of any kind of heat-insulating material. In particular flexible, fire-resistant and high vapour permeability materials may be used. Thus wetting of the material to be caused by concentration of humidity is minimised. • The ventilation air-gap between the shell and the heat-insulating material is achieved through a free support of the shell on wide-flange supports of appropriate height, which may even be based on the relatively soft surfaces of the heat-insulating material and which cause slight if not negligible deformations of the heat-insulating material, as a result of the uniform distribution of loads. The ventilation air-gap ensures that : a. the surface of the heat-insulating material remains dry, and thus there is no risk of reduction of its heat-insulating ability. b. energy losses of eventual over-heating or over-cooling of the shell are reduced. c. energy losses due to the influence of wind speed are limited. • The final surface formed over the ventilation air-gap, is a strong, monolithic, passable shell, with no expansion joints, made of a thin plate of reinforced concrete. • The shell remains crack-free and fully water-tightened for the entire life of the building, because of the particular reinforcement, its ability to slide upon the flanges of the supports, its inorganic composition as well as because of the mixing of the concrete with several additives. • The slight inclinations formed on the final surface of the shell for the guidance of the liquids towards the collectors ' inlets do no require the use of any particular and additional material. They are rather formed during the phase of application of the concrete and extend to an area which is proportional to the discharge capacity of the collector. • The final disposal of the water is obtained through a siphonic system which consists of the collector and the pipe connected to it. These elements, with the exception of the collectors inlets, are immersed in the ventilation air-gap and are freely based on the surface of the heat insulating material. The method above described is only a way of carrying out the invention, which is not limited to it. Additions, modifications or even removal of features is possible, provided that the method lays within the definition of the invention, in accordance with the claims, which follow. For instance, the shell sliding on the supports may be pre-fabricated, rather than being constructed in its final position.

Claims: Claims 1. Method for heat insulation of roofs and floors, the said method comprising the following steps: a. positioning a layer of heat-insulating material (2) on the upper surface (1) of said roof or floor, b. placing supports (4) on the said heat-insulating material (2), c. constructing a shell (7), the said shell (7) bridging the said supports (4), so that an air gap (3) is formed between the said heat-insulating material (2) and the said shell (7) and so that the said shell (7) may slide freely on the said supports due to thermal movements (4), whereby said shell (7) is monolithic, rigid and waterproof, and is made of inorganic material, and whereby the said air-gap (3) communicates with the outer space, for the ventilation of the said air-gap (3). 2. Method for heat insulation of roofs and floors according to claim 1, whereby at least one water collector (8) is placed between the said heat-insulating material (2) and the said shell (7), the said water collector (8) comprising an inlet (8a) and an outlet (δβ), whereby the said inlet (δa) remains outside the said air-gap (3) and the said shell (7) does not cover the said inlet (δa), and whereby the said outlet (δβ) is within the said air-gap (3) and is connected to a pipe means (9), for siphonic drainage. 3. Method for heat insulation of roofs and floors according to claim 2, whereby the said water collector (δ) comprises a ventilation channel (δ ' ) for the ventilation of the said air-gap (3), and whereby the said ventilation channel (δ ' ) comprises a first opening (δ " ), which remains outside the said air-gap (3) and a second opening (8'") within the said air-gap (3). 4. Method for heat insulation of roofs and floors according to claim 3, whereby thread means are formed on the walls of the said first opening (δ " ) of the said ventilation channel (8 ' ), for a waterproof connection of the said ventilation channel (8 ' ) with a ventilation pipe. Method for heat insulation of roofs and floors according to any of the claims 1 - 4, whereby the construction of the said shell (7) comprises the following steps: a. either placing a prefabricated assembly or constructing an assembly (5,6) on the said supports (4), the assembly (5,6) comprising a reinforcement means for concrete and further comprising a barrier not allowing concrete, which is eventually applied on the said assembly (5,6) to move through the said assembly (5,6), whereby the said assembly operates as a framework for concrete, b. applying concrete on the said assembly (5,6), to form the said shell (7). 6. Method for heat insulation of roofs and floors according to any of the claim 1 - 5, whereby the perimeter (7 ' ) of the said shell (7) remains free. 7. Method for heat insulation of roofs and floors according to any of the claim 1 - 6, whereby the surface (1) on which the said method is applied is curved. 8. A heat insulating structure on the upper surface (1) of a roof or floor, whereby a layer of insulting material (2) is provided on the surface, and whereby a passable shell (7) is positioned over the surface on supports (4) located between the surface (1) and the passable shell (7), so that an air gap (3) communicating with the outer space is formed between the surface and the shell, which shell (7) may freely • slide on the said supports (4) due to thermal movements, and which shell (7) is monolithic, rigid and waterproof, and is made of inorganic material. A heat insulating structure on the upper surface (1) of a roof or floor according to claim lO, further characterised in that the layer of the heat insulating material is placed on the roof element and below the supports, and that the supports abut the heat insulating material, so that an air-gap exists between the insulating material and the shell.

Inventors: IOSIFIDES MINAS, IOSIFIDES, MINAS
Applicants: IOSIFIDES MINAS, IOSIFIDES, MINAS
Application year: 1994
Main classification: E04D11
IPC codes: E04B7, E04D11, E04D13